madbeanpedals::forum

Projects => General Questions => Topic started by: SlaveUnit on November 18, 2018, 04:08:39 PM

Title: 2N2646 Testing Methods (Vox Repeat Percussion Issue)
Post by: SlaveUnit on November 18, 2018, 04:08:39 PM
Can anyone please tell me if these are valid tests for a 2N2646 transistor? I ordered 10 and they are all failing with no readings.

http://www.circuitstoday.com/testing-a-ujt

If they are not valid could anyone please suggest other tests? Thanks everyone! I've been pulling my hair out with a percussion tremolo build.
Title: Re: 2N2646 Testing Methods (Vox Repeat Percussion Issue)
Post by: SlaveUnit on November 19, 2018, 05:22:15 AM
I think I figured it out. I'm pretty sure that I bought fakes.
Title: Re: 2N2646 Testing Methods (Vox Repeat Percussion Issue)
Post by: somnif on November 19, 2018, 05:46:06 AM
I had problems getting the repeat percussion to work with the 2646. I had a store in town that sold authentic NOS, but they were too expensive for me to keep buying them in hopes of getting one that would cooperate.

I eventually ended up going with a 2N6027 and slightly modifying the circuit (add one resistor, change the value of another) and got my choppy skippy goodness.
Title: Re: 2N2646 Testing Methods (Vox Repeat Percussion Issue)
Post by: somnif on November 19, 2018, 05:56:37 AM
The modifications -

(https://i.imgur.com/IYsliea.png)

May require twisting the legs of the transistor depending on your layout, but that's about it.
Title: Re: 2N2646 Testing Methods (Vox Repeat Percussion Issue)
Post by: SlaveUnit on November 19, 2018, 02:17:22 PM
I ordered more from another seller. If those are fakes I may give this a shot. Thanks for the info.
Title: Re: 2N2646 Testing Methods (Vox Repeat Percussion Issue)
Post by: chongmagic on November 20, 2018, 09:30:06 PM
Quote from: somnif on November 19, 2018, 05:56:37 AM
The modifications -

(https://i.imgur.com/IYsliea.png)

May require twisting the legs of the transistor depending on your layout, but that's about it.

I have been wanting to try this in the clone of the Hummingbird from PedalPCB, the 2N2646 makes a lot of ticking and I would like to try replacing  it with a 2N6027, I will look at the schematic and see if I can make it work.